Glass is a material which can be seen as a double-edged sword. Its monolithic, smooth, and transparent look transmits a sense of elegance and simplicity. However, due to its brittle mechanical property, it can create complex engineering challenges when intended for a structural load-bearing application. Many forget glass has a comparable compression strength to steel and excels when compared to the mechanical properties of unreinforced concrete. (Oikonomopoulou, 2019; Ashby, 2006) Until now, there have been 4 primary discovered manufacturing techniques for glass. Float glass has a 25mm thickness limitation. (AGC, 2019) Extruded and float glass cannot form complex 3D geometries. (Roeder, 1971) 3D printed glass is not structurally validated. (Klein, 2015) Cast glass can offer a solution to all of these limitations. (Oikonomopoulou, 2019) This thesis answers the following question: To what extent can topological optimisation and new fabrication methods be employed to create compressive free-form glass structures? To answer this this thesis will delve into glass, topology optimisation and shell structures. Throughout the thesis it will notice how topology optimisation and shell structures offer solutions to glass related challenges. Compression Shells are ideal for Glass. Why? Because glass is brittle. This means that it fractures without warning when tension is applied to a crack. Glass has a low tensile strength but a very high compressive strength. That is why shell structures are ideal for glass as they experience compression only loads. (Adriaenssens et al., 2014) Shells best utilize the strengths of glass and avoid testing its weakest limitations. Annealing time is one of the most challenging aspects of cast glass. As the volume/mass ratio increases the annealing time increases exponentially. (Oikonomopoulou, 2019) This means careful consideration should be attributed to decreasing this time. This thesis used topology optimisation as a tool to decrease the thickness and thus the annealing time. This thesis explains structural optimisation and evaluates different topological optimisation approaches and software. At the end a 43% mass reduction was achieved. The goal in this thesis was to design an 6x6m booth from cast glass for the martial district exhibition. After the shell was topologically optimised and structurally validated by means of finite element analyses, the booth was designed for manufacturing, transportation and assembly. The booth was subdivided to fit in trucks and be assembled using spider cranes. The manufacturing procedure was developed using additively manufactured sand mould designs. Demountable and reusable connections, and foundation designs were also developed for the shell.

The building industry is a significant waste contributor. Especially at the end-of-life of the building it causes an enormous impact on the environment. Construction solid waste has caused serious environmental problems. Reuse, recycling and reduction of construction materials have been advocated for many years, and various methods have been investigated. However, the effectiveness of its applications seems limited. Waste will be reduced by extending the lifetime of the materials giving the second life.This research aims to the design of a construction component made of reused train windows of the old VIRM trains of NS. The continuous flow of the train windows due to the renovation of the trains demands a multiadaptable solution that offers different design scenarios.

Current research conducted at TU Delft focused on utilizing structural Topology Optimization (TO) for designing large monolithic cast glass structures with maximum stiffness and minimum mass. These structures demonstrated improved manufacturability in terms of time, energy, and cost efficiency due to their mass efficiency, which results in shorter annealing times. However, the complex geometries and customization of these forms posed challenges in terms of fabrication. The manufacturability of intricate glass structures is explored by analysing and comparing three possible fabrication methods for three-dimensional glass structures with complex and customized geometries. The methods examined are: (i) Kiln casting in disposable moulds, (ii) Waterjet cutting and lamination of float glass panes, (iii) Additive manufacturing of glass. The assessment of these methods is based on a set of criteria related to structural performance, visual quality, fabrication limitations, and sustainability. This comparative study act as a guide to the design of a case study and the selection of the preferred fabrication method. An all-glass topologically optimized bridge observatory in Vikos Gorge, Greece, is chosen as the design case. Based on the comparative study and a set of soft criteria, casting in disposable moulds is selected as the preferred fabrication method. However, glass casting currently faces major drawbacks that restrict its potential. The two main drawbacks that this thesis tries to address are: Rough and opaque surface quality (main focus): This issue is tackled through laboratory experimentation with the aim of achieving good surface quality immediately after demoulding. The experiments involve the use of different types of disposable 3D printed sand moulds (3DPSM) and application of refractory coatings and coating combinations at various maximum firing temperatures. Lack of redundancy: Redundancy is explored though research by design and the implementation of design strategies (segmentation, zoning, fabrication methods combination) to ensure the feasibility of the structure. The end result of this thesis is a comprehensive study on how an all-glass structure with complex and customized shape can be realized. The experimental part of the research yielded improved results, indicating that the combination of refractory coatings and 3DPSM has the potential to bring such glass components to life, reduce the need for post-processing, and simplify the fabrication process. Given the limitations of time and knowledge within a master’s thesis, further research is suggested to validate and evaluate the results obtained.

Transparency is embraced more and more in contemporary architecture and therefore glass has become one of the most important materials in the building industry. In structural glass applications the elements are dimensioned based on stiffness and strength requirements. This research investigates the potential of glass sandwich structures as a way to create planar elements with a high stiffness to weight ratio and reduce material consumption in structural glazing applications. The design focuses on the replacement of the glass floors of the Acropolis Museum in Athens with an aim to a)reduce material consumption, b)eliminate the supporting substructure and c)propose an optimised design. 7 different core topologies are designed and tested by means of a 4-point bending test in a way to assess the optical quality of such structures, showcase their potential and finally assess which configuration is the most suitable to be used in the aforementioned application. The topology that fulfills the structural and aesthetical requirements is furtherly investigated and its structural behaviour is “deconstructed”. The knowledge acquired through this process is used to optimise structurally and aesthetically the panels of the new glass floors.. Finally, a design toolbox is devised which constists of three phases: a)graphical/analytical calculations (predimensioning), b)Finite Elements Analysis (detailed calculation) and c)Bending Tests (evaluation). In general, this research proves the advantage of glass sandwich structures over laminated glass in stiffnes-dominated designs but also discusses the importance of integrating the process of selective distraction into the design.

Glass has been widely used in the construction industry since the early nineteenth century. It was most commonly used in the form of a window, which is a flat glass panel. Glass has natural optical properties and is resistant to weather, making it ideal for use as a facade material. Glass’s novel applications in the built environment have led us to go beyond its 2D application of flat glass panels to a solid, 3D component, as seen in recent projects such as Maison de Hermes in Tokyo and Crystal House in Amsterdam. Currently, there are two approaches in glass blocks: load-bearing solid glass blocks with poor thermal properties and hollow glass blocks with optimal thermal properties but no structural performance. Can we combine these approaches and develop a glass block with good load-bearing and thermal properties? Research on Hybrid glass blocks is one such topic that investigates the potential of this unique concept. A hybrid glass block is the combination of solid and hollow glass blocks designed as a single product with good thermal performance and load-bearing capacity. The existing research on this topic is promising and noteworthy for further development as it conceptualises the rudimentary design guidelines for the system. The output of the existing research is oriented towards the design development of the novel hybrid glass blocks, ideation of the production methodologies, and validation of their thermal performance. Thus the scope for further research and development is actual prototyping of the design concepts, validation of the structural performance, and qualitative analysis. It is observed that the shape of the hybrid glass blocks impacts the structural-thermal performance, production methodology, and desirability of standardisation. Thus, to develop this product a thorough investigation and exploration are necessary. The research first focuses on developing design guidelines for the innovative hybrid glass system. A product development methodology is formulated to guide and aid the design process of the hybrid glass block systems. Various design concepts are explored in-depth for each design problem based on their relationship with the structural-thermal performance, manufacturing, and assembly process and are then assessed through a set of design criteria to develop a final design concept. The final design concept is further refined based on manufacturing standards and challenges. The final design is then detailed and implemented in the Academy of Arts, Maastricht (case study), and various assembly strategies for dry stacked cast glass systems are formulated. To validate the design a prototype manufacturing is done by using a kiln casting method. The prototyping challenges, observations, and decisions aid to assess the practicality of the design. A hybrid method of numerical and experimental validation is considered to evaluate the design based on its feasibility for application in the building industry. This research proves to be a guide for developing hybrid glass block systems and provides them with a design development, manufacturing, and evaluation framework to design, develop and assess their concepts.

This thesis is part of a larger ongoing research project at the TU Delft regarding structural glass as a novel construction material. Here, the focus is directed towards the casting of glass to create complex free-form geometries. Thus far, only smaller components have been created, but a multitude of previous student work explored how the current limitations in the fabrication process could be overcome by using topology optimization to design larger cast glass components. This thesis continues this research by integrating the limitations and remarks concluded from previous work to further explore the potential of designing large cast glass components using topology optimization. This thesis intends to contribute to the existing research by creating a tool for the design of 3D optimized cast glass components, which can take into consideration the structural properties of glass as well as manufacturing, annealing and specific design criteria. The tool is created in Matlab, using the SIMP optimization method with 8-noded hexahedral finite elements for the structural model. From the literature review it was concluded that the SIMP methodology is best suited the requirements of this project. For the structural model, 8-noded hexahedral elements were selected. Two algorithms were developed: one with a compliance based objective and a second with a volume based objective. The algorithm’s performance was tested on different domains. To facilitate comparison with existing literature, the algorithm was initially calibrated with a domain width of one element, effectively creating a two-dimensional optimization. Subsequently, its performance was assessed through the application of a small three-dimensional problem. Finally, the algorithm is used to design a case study involving the structural slab of a small pedestrian bridge located inside the British Museum. The results validate the benefits of the 3D algorithm. The geometries optimized in three dimensions have a higher structural stiffness and offer more spatial insight. Moreover, the volume optimizations results in a larger material reduction than those achieved in two-dimensional optimizations. For this reason, the volume-optimized component was selected for post-processing and implementation in the final design.

Cast glass is a promising structural material that has seen increasing use in the build environment over the last year. It offers a great freedom of shape for designers and engineers, beyond the two-dimensional float glass that is still primarily used. Despite this, cast glass in practice has only been used for solid bricks, mimicking traditional ceramic brickwork. Little exploration has been made on the complex shapes that can be achieved in cast glass. One of the largest challenges of cast glass is its slow and meticulous cooling process required after casting, to prevent the occurrence of internal stresses. This costly annealing process is the main limitations for producing large scale cast glass elements in an affordable way. Experience in large scale solid glass mirror castings performed for NASA show that annealing times can be reduced through smart design. Structural topology optimisation is a design tool for creating light-weight, material efficient elements. Its application has mostly been limited to industrial and aerospace design, though it is slowly being introduced in the built environment as the additive manufacturing required for these geometries becomes more advanced, and affordable. So far, topology optimisation of cast glass design has remained unexplored. The goal of this thesis is to investigate the potential of using topology optimisation as a design tool for complex structural cast-glass elements with a reduced annealing time. For this, a complex-shaped grid shell has been redesigned in glass, using optimised cast glass nodes. The entire fabrication process, from digital design, to physical fabrication using additive manufacturing has been explored.

Glass is a versatile material applied in a large number of industries. It can for example be found in everyday household items, inside high tech machines or it can be used as part of mechanical structures in buildings. This research focuses on using structural cast glass components for a dome design forming a sustainable living habitat for Lori parrots in a moderate climate while being minimum invasive for the local environment

Glass is one of the oldest building materials used in the building envelope. Its attractiveness to architects, designers and users is mainly due to its fascinating ability to combine two otherwise contradictory functions; to separate and protect the interior from the exterior environment while at the same time allow for openness by letting daylight penetrate the space. Apart from the apparent and basic function of transparency, glass, if properly designed, can fulfill almost any role in a building structure, from insulating a facade, to taking building loads besides its own weight and the imposed wind forces. Especially in terms of a building’s thermal performance, the assembly of single glass panes into insulated units is a colossal advancement for the building sector towards more sustainable structures since it allows the creation of fully glazed facades with minimised thermal losses. However, the use of insulated glass units while improves greatly the energy conservation of glass buildings, it neglects to account for the impact of this assembly procedure on the waste streams the materials used create once their service life is over. Currently, there is no provision for extending the life-time of IGUs by the means of reuse, refurbishment or recycling and consequently they end up being discarded in landfills after a limited time of use. For this reason, it is crucial to design an alternative IGU that abides by the laws of circularity, meaning the use of design approaches with an end-of-life plan for new products used as construction elements. Such a circular approach could greatly benefit the transition from a linear to a circular economy which is indispensable for the building sector since it accounts for a large amount of construction and demolition waste that end in landfills every year. The pollution from these wastes could be significantly reduced if the products applied were initially designed to be used in a circular way instead of having a single-life character. The current master’s thesis focuses on the exploration, through detailed design, of the different ways in which an insulated glass unit can become more circular without compromising its transparency. The term circularity here refers to a design that tackles the end of life of the unit by facilitating its remanufacture in case its thermal performance starts decreasing; the reuse of parts of it or of the whole unit, and the recycling of the glass panes when neither reuse nor remanufacture are an option. Moreover, the aim is to create an IGU that is as transparent a possible by minimising the optical result of the current IGU edge seal connections. In order to create a circular IGU, firstly, contaminating factors on the glass surfaces that could hinder their recylcability should be avoided. Secondly, a reversible way of connecting the different glass panes that comprise the IGU is opted for. Currently used IGUs have edge seals that consist of an element called a spacer bar and sealing elements that ensure the structural stability of the unit and prevent the air and moisture diffusion to the cavity. The element that connects the glass with the spacer bar in the current IGUs is a strong structural adhesive of black colour that cannot be removed without contaminating the glass. This is precisely the element that this thesis aims at replacing through an alternative connection design that enables the reversibility of the unit and the reduction of the optical impact of the edge seal. The design exploration phase led to a final design that achieves the initial goal using an innovative alternative connection that replaces the spacer bar and secondary seal of a typical IGU with two cast glass elements each fused to the edge of the float glass panes. The connection of these cast glass elements occurs with the use of a simple mechanical clamping element, a metal spring clip that can be easily applied and just as easily removed. The small dimensions of this clip and its application internally between the float glass panes ensures the reversibility of the edge seal as well as its improved optical result. The final design remains in a research stage proposal and further testing would be necessary regarding its thermal performance, its structural rigidity and the assurance of its good weather sealing. However, this research through design exploration concluded to a feasible, in theory, design that achieves the initial goal.

The wide application of glass in buildings is due to its innate transparency and durability. This quality has led to the development of hollow glass blocks during the industrial revolution. These blocks are durable, fire-resistant, exhibit heat resistance, and sound deadening properties. In recent years, new explorations have begun to uncover the structural potential of glass. It is no longer just a cladding material but is also being used for load-bearing applications due to its high compressive strength. One of the most significant drawbacks of cast glass bricks’ current systems is the unsatisfactory thermal performance due to the absence of a cavity and the thick cross-section, which acts as one thick single glazed unit. On the other hand, hollow glass blocks are non-load-bearing due to their thin cross-section of the inner wall which results in buckling under a load and thus, the system is susceptible to failure. A promising solution to these problems is to develop a block that can exhibit structural strength and thermal insulating properties. To do this, design guidelines were developed by carefully studying both the systems followed by different design options which were analysed for their thermal performance. It was observed that the incorporation of cavity, inert gas and coatings greatly influences the thermal property. Also, the presence of continuous glass cross-section is important for structural integrity which generates thermal bridges that negatively impacts the thermal performance of the system. This analysis resulted in two different design options; the fusion block and the lattice block. To fabricate these blocks, careful consideration was taken in the design of the moulds and the chosen glass type. For the two designs, two separate connection systems are employed; one an embedded connection and the other an interlocking pattern. Both connections generate a dry assembly system which is reversible, easy to assemble and easy to maintain. To understand the feasibility of the proposed design solutions, a case study of Ports 1961 store in Shanghai was considered. The blocks were applied on the façade of the building and this was then analysed based on the developed design criterions. The proposed blocks have better thermal performance values, optical and aesthetical qualities. The installation process is much simpler and reversible. The fabrication process is however complex but that is due to the absence of standardized manufacturing system for cast glass bricks. The present research does not conclude in a single suitable design option but rather two concepts. The exploration of different concepts for thermal performance, it’s fabrication and installation results in a general understanding of the parameters that affect the development of this technology. To realize the proposed system, structural verification, fire safety and acoustics still need to be carefully considered and additionally this need to be validated experimentally to derive statistical data for its safe application. Nonetheless the performance values indicate a great potential in the technology.

The current thesis aims to explore the potential of producing large-scale structural cast glass elements with the help of 3d printed sand moulds. Until now, mostly small blocks from structural cast glass have been generated in the building industry, revealing a research gap regarding massive components. Apart from the size, the unlimited shape potentials of cast glass have hardly been explored so far. This is because glass casting can be a very challenging process when it comes to the solidification of the material which needs to be completed under specific program settings. Except from the brittleness of the body during the annealing process, it can take months, even years for a large-scale element to be completed, because of the full controllable conditions under which the annealing process takes place. In addition, the mould types that are currently used for cast glass components present several restrictions such as the manufacturing costs, the accuracy or the sizing. An existing glass slab in the Acropolis museum, in Athens, was chosen to embody the research goals. The slab is located on top of archeological discoveries making the need for transparency necessary. The current slab consists of float glass panes with a concrete substructure which severally restrains the viewing. The thesis aim is to develop a free-form monolithic slab exclusively from cast glass without the need of external substructure. In order to address the above demands, the topology optimization method was introduced. Several algorithms of topology optimization have been developed. A compliance-based optimization was demonstrated as the most appropriate for the specific project. Obtained from the literature framework, the main principles that the design follows gravitate towards the structural, cast glass and manufacturing requirements. The external applied load, in addition to the allowable structural values were calculated. The importance for a flat upper surface, where a safety float glass layer of a permitted deformation should be laminated, was established. Regarding the cast glass demands, it is necessary to acquire a design with smooth surfaces, round edges and uniform distributed material throughout the entire model. For the current project, the optimized slab is decided to mainly consist of borosilicate glass.. A slab separation is crucial for transportation reasons. After the definition of the main design principles that the final product should respect, the design development was conducted with the combination of three methods: topology optimization, manual design and structural validation. The final result of the optimized slab successfully fulfills the preset design criteria, as the obtained structure presents 55.2% less mass than the solid version that was initially designed to replace the existing slab in the museum. In addition, a more efficient material distribution in the optimized model renders the slab more compatible for the cast glass annealing process. The result of the topology optimization technique was a quite complex geometry which is not that effective to be produced in the conventional moulds that are currently available for cast glass applications. Therefore, a new technique needed to be explored, which follows the 3d printing evolution in the building industry. The main restriction of the printed moulds is the limited available sizing that the commercial printers provide. As a solution to this problem, the separation of the large-scale mould into smaller segments was studied, as well as the development of the connecting system of these parts. The entire fabrication technique, from the moulds printing method, to the assembly components and glass melting was investigated. Finally, the transportation and integration of the slab into the building was explored, concluding with structural solutions that respect the museum and the assembly order that the slab can be attached on it.

Glass has become ever more popular in the building industry. Glass is already used in facades, staircases, fins, floors, and beams. Nevertheless, free-standing load-bearing glass columns are rarely used. It needs to be robust, which means that it needs to give a warning before failure so that people can evacuate. Glass is a brittle material and has a sudden failure, which means that it is not directly logical to use solid glass as a load-bearing structural column. Rather despite the high compressive strength, due to complications with manufacturing, spontaneous failure, and lack of satisfactory of fireproof performance, more research needs to be done on the manufacturing, the fire safety, and the robustness of glass columns. In the literature study, the layered tubular glass column was found to be most promising for further investigating. The aim of this research is to design and engineer a transparent tubular glass column as a structural element, which is robust and fireproof. In the literature study a few aspects emerged: the tubular shape, the column needs to be sealed to avoid the column from becoming dirty, end connections, the geometric tolerances in the glass tubes and the robustness. The designs were engineered for the case study Bouwdeel D in Delft, but the designs can also be applied to other buildings: the fire resistance, demountability, the dimensions and the calculated compression loads. With these aspects in mind, three designs were engineered, the MLA (Multi Layered with Air) (2x) and the SLW (Single Layered with water) (1x) which fulfil the defined design criteria/main concerns. Six small samples with a length of 300 mm were produced to test the lamination process with regard to bubble formation and possible breakage of the glass by internal stresses. Three laminated DURAN (annealed) samples and three laminated DURATAN (heat-strengthened) samples were tested. The glass tubes were manufactured by extruding and were made by SCHOTT. H.B.Fuller Kӧmmerling carried out the lamination process. Furthermore, the connection components (steel and POM) were produced and arranged by Octatube, the steel hinges were arranged by Techniparts, and the Hilti mortar was arranged by Hilti. Afterwards, these samples were tested on compression strength, to investigate the behaviour of the interlayer material, the post-failure behaviour of the designs, the differences between annealed and heat-strengthened glass samples, the behaviour of the connections under pressure, and the capacity of the glass tubes and the connections. The first cracks appeared earlier than expected. Nevertheless, the samples seemed to be really robust, because the samples had a large load-bearing capacity even after the first cracks occurred. The first crack appeared between 95-160 kN in the DURAN samples, and after that the samples were still able to carry a load of 700-750 kN. So, after the first crack, the specimens were able to have around 4-5 times more load. The heat-strengthened samples first cracked at 120-160 kN. The maximum force of these samples was 390-490 kN. This means that after the first crack, the specimens were able to have around 3 times more load.

This thesis is about reconstructing historical vaults with cast glass. The vision is to design a complete dry-assembly cast glass arch vault where the Notre Dame de Paris is the chosen case study. The main question is: To what extent can a historical masonry arch vault be reconstructed by using cast glass components? The method is based on literature research and FEA simulations. The thesis contains three main phases of the research. First, the background, problem statement and research objectives/ questions are discussed in the introduction. Then, the complete literature research where heritage, arch vault structures, structural glass and cast glass in structures will be discussed. The third part describes the complete design phase including the criteria and final design. The thesis finishes with a conclusion and discussion chapter. The main results of this thesis are that a historical arch vault can be reconstructed from cast glass, but this will bring high risks and costs. Therefore, the suggestion is to use cast glass for the structural arches as this meets the complex geometry but use traditional materials for complex nodes and float glass where single, abstract curves can be made. The connections between different components are dry thanks to interlayers, but the cast glass elements are adhesively bonded. From safety, assembly, and labor perspective, these connections are chosen. This way, the blurry effect of glass in a heritage is reached, but the method is simplified. This principle can also be applied as roof structures for future buildings, but also for small pedestrian bridges as the geometry possibilities are unlimited.

This thesis continues the investigation in the direction of exploring the potential regarding the use of Topology Optimization techniques for the design of cast glass structures. Previous theses in TU Delft have underlined the large potential for the design of these megaliths, but at the same time they have also underlined the strong limitations that derive from the use of commercial software as the tool for it. The limitations are directly related to the brittle nature of glass which results in significantly different behavior regarding its maximum tensile and compressive allowable limits. This renders fundamental to be able to evaluate both of these criteria during the optimization process. If this is not possible, as it was the case in the previous theses, a secondary (post-processing) phase should be integrated in the process in order to alleviate the peak stresses that may occur in the structure. This increases significantly the time and effort needed for the design and, therefore, it was underlined as an issue to be tackled in further exploration. This thesis aspires to address this problem with the creation of a customized optimization tool that takes all the structural constraints into consideration and, additionally, integrates the criteria specifically related to the glass manufacturing process, such as the overall annealing time needed. The tool is created in Matlab with the use of Finite Element Method equations in order to develop the structural model. The results of the structural analysis were validated through comparison with results obtained through ANSYS. The literature review covers a wide scope of topics. Firstly, the glass properties and the casting process are investigated in order to properly indicate the criteria and constraints that arise in every phase. The second part refers to topology optimization. A comparative review of the different algorithmic methodologies is realized and SIMP is selected as the most appropriate for the project. Additionally, the different categories of formulation for the optimization problem – stress, compliance and volume based – are discussed in order to select the appropriate objective and constraints. At the same time, a review of the previous theses is realized in order to indicate which method was used in every case and how the constraints were integrated in the process every time. In the end two different algorithms are developed based on two different problem formulations; one with compliance objective and a second one with volume objective. The aim is to investigate if the volume objective optimization can be a robust alternative to the classical compliance approach leading to more lightweight structures which at the same time fulfill the criteria regarding their feasibility to be manufactured. Firstly, the performance of the algorithm in relation to each objective and constraint individually is evaluated though application in a smaller scale benchmark problem. The results showed that all the setups work and, therefore, they can be used for the final design experiments. However, it also indicated that some constraints, such as stress, cannot be applied individually but they always have to be combined with another constraint that guides the optimization in order to lead in a reasonable result. Afterwards, a combination of objective and constraints for each of the two aforementioned formulations – compliance and volume - is tested and applied in the case study example which refers to a slab that serves as a small pedestrian bridge inside the British Museum. The results validate the estimation that a volume-based problem formulation can offer a robust result which resembles the result obtained from the traditional compliance-based formulation. Moreover, the result in the volume-based case is clearer and sharper and for this reason it was selected in the end for implementation in the final design. The formulation is then used in combination with different glass types, boundary conditions and design domain in order to conclude to the final shape of the slab.

Glass is a material that has a high compressive strength and a low tensile strength. While being mostly produced as flat sheets of float glass, it can also be casted into components that have a thicker geometry and thus a higher buckling resistance. These properties make cast glass components suitable for the construction of shell structures that are mainly subjected to compressive stresses. Shell structures often have the shape of surfaces with varying Gaussian curvature. When constructing such a shell structure out of cast glass components, components of varying geometries are needed. During this research, an adjustable mould was developed that can be used for the casting of glass voussoirs of varying geometries. The possible voussoirs geometries that can be cast in the adjustable mould are limited to voussoirs with planar, convex polygonal intrados and extrados. These voussoirs can be used to construct fully transparent shell structures. The voussoirs are dry-assembled with an interlayer in between that compensates for any production tolerances and avoids glass to glass contact. Furthermore, by using dry-assembly instead of an adhesive as a bonding method, the structure allows for disassembly and full recyclability. Tongue and groove shaped interfaces ensure an interlocking connection. The interlocking connection prevents any lateral movement and will guide the voussoir into the right position during assembly. By tessellating a shell structure, the shell structure is divided into a discrete number of voussoirs that can be cast in the adjustable mould. Several aspects have to be taken into account when optimizing the tessellation pattern including planarity, alignment to the flow of forces, face size, interior angle size and if the pattern is staggered or not. A comparison was made between three different regular tessellation patterns (triangular, quadrangular and hexagonal) with these aspects kept in mind. A shell structure was designed to cover a courtyard of the Armamentarium in Delft. This shell structure served as a case study used to demonstrate the design and production process developed for this thesis. The shape of the shell was generated through a form finding process and its structural performance was validated with a FEM analysis. The shell was tessellated into a triangular tessellation. An algorithm used for assigning either tongues or grooves to the interfaces of each voussoir was developed. A list was generated containing the following information for each voussoir: voussoir index number, interface types, edge lengths, voussoir joining angles and the adjacent voussoir index numbers. The data in this list serves as input data for the set-up of the adjustable mould. Furthermore, the connection between the shell structure and the existing structure was designed and an assembly method was developed.

The search for a transparent, reversible, and reusable consolidation system for monuments led to the ambition to test possible cast glass interlocking brick designs using numerical calculations. The focus of this research is hence the design, simulation and evaluation of a possible cast glass interlocking geometry using Finite Element Analysis (FEA). For this purpose, design criteria are formulated from literature; considering glass, polyurethane (used as interlayer) and interlocking systems. As interlocking systems are determined by their boundary conditions, a case study of a monument is chosen to provide additional design criteria. The goal of the case study is to provide a reversible and reusable restoration and consolidation alternative for the current invalid restorations. The design criteria obtained then are combined into an initial geometry, whose parameters are varied to test their sensitivity to its shear capacity, using FEA. Christensen’s failure criterion is used to locate prone areas in the geometry, and to evaluate the theoretical moment of failure. This output value combines the three principal stresses into a failure envelope, hence can generate contour plots to envision peak-stress-prone areas. This is important especially for glass structures, as they are prone to peak tensile stresses. From the results design diagrams are created and applied on a conceptual cast glass interlocking consolidation design for the monument chosen as case study: The Lichtenberg Castle ruin. The initial design is moreover prototyped to check its interlocking capabilities, residual stresses and deviations introduced by shrinkage. Being able to evaluate possible geometries using FEA can decrease costs and time when searching for a new interlocking geometry. Prone areas are easily highlighted using the Christensen’s failure criterion output. Hence peak stress sensitive or invalid geometries can be discarded before reaching the prototyping stage, which is time consuming and costly. The creation of a methodology to predict this behaviour is hence valuable for further research on other cast glass geometries and can moreover be applied in any other field when analysing solid complex geometries. Another goal is to find a cast glass brick design which not only can consolidate the monument of the case study, but is moreover applicable in other projects or configurations. The brick then is not a one-solution design, but can be reused in other projects. The geometry hence is varied using Grasshopper plug-in for Rhinoceros. By exporting the geometry using a STEP-file, a solid can be loaded into DIANA FEA, where it can be analysed using their newly implemented output value of the Christensen’s failure criterion. The geometry of the monument is gained through a 3D laser scan, resulting in a point cloud. The point cloud is adapted using Autodesk Recap, then further processed in Rhinoceros. The Christensen’s failure criterion output is a proper and fast way to evaluate possible cast glass brick designs. Any compressive stresses on the interlocking brick geometry are beneficial for its shear capacity, as is an increase in interlocking amplitude or brick height. Increasing the amplitude however affects the allowable tolerance negatively, which is also the case for a decrease in brick height. Decreasing the brick height hence results in both negative effects. The conceptual design for consolidation of the Lichtenberg Castle tower can replace the current interventions with equal or higher capacity, even for all conservative assumptions and simplifications. The design can still be altered less conservative after more experimental results and simulations come available. The methodology applied can now be further developed and performed on other complex geometry designs. The presented multifunctional cast glass interlocking brick design, and its variations can be further investigated and applied in other projects.

Dense urbanization increases the demand on the building sector who is responsible, on the one hand for producing large amounts of landfilled glass waste, and on the other for consuming the earth’s natural resources and release additional CO2 emissions, for the manufacture of new architectural glass. These unfavorable conditions together with the already apparent effects of climate change, demand resourceful solutions for adaptive and resilient cities, that utilize current waste and require low maintenance and low costs, to be implemented universally. This, can only be ensured by letting nature to take over. Unexploited urban facades have a key role to provide this new ground that can be colonized by microorganisms, creating a microclimate by forming an outer green layer growing on its own. Aiming this, materials covering our urban facades need to be transformed to porous hosts by retaining rainwater and providing the right environment for bio-growth to take place. This research aims to discover new ways that unutilized glass waste can be upcycled into bioreceptive applications, that form a promising set of criteria. By shedding light firstly on the specific material properties needed, the method of glass foaming is chosen to be investigated, as the means to provide an open porous network that can incorporate large amounts of waste into its recipe. An experimental approach has been designed to explore the parameters related to the mixture, manufacturing process affecting the glass foam’s microstructure and potential biofilm formation by producing a total of 22 samples in the Glass lab in Stevin lab, TU Delft. These specimens were not foamed at once, but gradually being tested first of all, microscopically, to reveal the porosity network and secondly, with a series of quick tests related to their hydraulic performance, providing feedback for the next batch of samples regarding the most promising recipes to be further explored. All the samples were tested for their water absorption, evaporation rate and frosting resistance, while only the higher-scored specimens were put under test for moss-growth and compressive strength. Apart from the experimental analysis, the next steps towards a product development were also explored by setting the bioreceptive design principles for manufacturing the meso-scale surface. Limitations in adjusting these guidelines to the way glass-foam is produced are addressed with possible solutions as suggestions for further experimentation. In addition, an application catalogue was composed as schematic recommendations to showcase the potential of bio-host glass. Combining this idea to the material science, these applications were also approached from an engineering view to analyze the material properties’ specific demands per product. This tool, can prove to be beneficial both in the hands of the future designer and material researcher to have a starting point on what needs to be further developed, depending on the chosen product out of bioreceptive glass-foam. Taking the most immediately feasible example of a façade tile, based on the findings of the aforementioned analysis, during the last part of this project, a methodology for designing and implementing the new material into the urban environment is proposed. By informing the design of the macro-scale with weather data, precipitation levels can be exploited, in order to provide the maximum water content for the benefit of bioreceptivity. Therefore, the novelty of this thesis, aspires by providing a holistic approach, based on the knowledge obtained both in the literature review and the conducted experiments, to stir not only bio-growth on our cities, but also innovative thinking and exploration on ways to combat the increasing landfill waste.

The high compressive strength of the material glass in combination with its transparency, make it an attractive material to use for a column. Though different types and configurations of glass columns have been subject of academic research, a demountable glass column made from laminated components remains unexplored. This structural concept allows for modular and temporary structures with incorporated structural safety. Assembly and demounting is quick and the smaller, laminated components give the column sufficient redundancy. Glass however, is notorious for its low tensile strength and brittle failure. Also, a column made from interlocking components introduces stability problems. A comprehensive understanding of this new type of glass column is necessary before application in the built environment is possible. So far, no numerical analysis has been conducted on columns made up of interlocking laminated elements, while this analysis can help understand the stability, force distribution and stress concentrations of such a system. The main objective of this research is to obtain a feasible all-glass column design. This is achieved by using a Finite Element Analysis(FEA) to investigate: stability, force distribution and stress concentrations. Furthermore, a variety of design aspects and trade-offs are discussed in detail. These structural and design considerations are used to iterate the column design and to propose a combination of parameters that leads to a feasible design. The FEA investigates the following structural parameters: component dimension, roof ballast load, façade stiffness and interlayer thickness. Different combinations of investigated parameters lead to a feasible, functioning column designs. The column is able to horizontally displace up to 9,1mm before becoming unstable. The heavier ballast load of 1,2kN/m2 is desired over the minimal value of 0,6kN/m2. The column is unable to take up a significant amount of the total horizontal case study load for all investigated component widths. It can take up up to 39% of the vertically applied load when a minimal amount of soft interlayers is used. The tensile stress concentrations stay within the allowable limits. The different design aspects investigated include: material constraints, fabrication limitations, safety and redundancy and assembly. Each laminated component is made of up 3x15mm thick annealed float glass plates, and is fit with a sacrificial layer on either side for protection. The glass plates are water jet cut into the desired shape and then laminated together to form the component. The shape of the interlock is gradual end rounded in order to prevent (tensile) peak stresses. The risk of damage has been minimised. Moreover, the glass column has sufficient redundancy because the laminated components retain sufficient bearing capacity in case of damage. Also, the structural glass façade serves as secondary loading path in the case of severe damage. This research serves as a starting point for future research and possible real-life application of a novel type of interlocking glass column. This type of column can be applied in demountable structures. Combinations of parameters have been proposed that result in a feasible, functioning column. Recommendations have been set up to improve future iterations of columns with a similar design.

This research investigates the potential of 3D printed sand moulds for casting structural glass column having optimised cross section. Conventionally, Glass, in architectural industry, has been used in form of sheets (Float glass) due to ease of fabrication of planar sheets, but in last few years, cast glass bricks have been used for creating structural wall/ envelope of few architectural projects namely, Atocha memorial (Spain), Optical house (Japan) and crystal house (Amsterdam) due to its high compressive strength. Cast glass offers many advantages over float glass, but, the reason for limited use of it, in the industry is due to annealing time. Thicker the section of glass, more time is required to anneal the element. To reduce this annealing time, one of the most promising solutions is to use an optimised geometry composed of thinner sections. These optimised geometries usually are based on stress and buckling load of the element; hence they have very dynamic geometry. In order to fabricate these optimised geometries, one has to take help from digital manufacturing tools involving additive manufacturing (3D printing). 3D printing of glass is still in very primitive stage and is currently used for creating artefacts rather than structural elements. Another alternative to fabricate these complex geometries is to print the moulds and then cast glass. 3D printed Sand moulds are being used in the industry to cast optimised concrete slabs and steel nodes. Hence this research explores the feasibility of 3D printed sand moulds for casting optimised structural glass geometries. A column design as a case has been taken, for the experiment as glass having high compressive strength, comparable to steel, portrays as a perfect material for a compression only structure. The column is structurally optimised using topological optimisation and sections of the complex challenging optimised geometry are fabricated using 3D printed sand moulds as different scale and results are drawn.